To copy the default style, load your project in Expression Blend and open the User Control that holds the RadButton. In the 'Objects and Timeline' pane select the RadButton you want to style. From the menu choose Object -> Edit Style -> Edit a Copy. You will be prompted for the name of the style and where to be placed.

If you choose to define the style in Application, it would be available for the entire application. This allows you to define a style only once and then reuse it where needed.

After clicking 'OK', Expression Blend will generate the default style of the RadButton control in the Resources section of your User Control. The properties available for the style will be loaded in the 'Properties' pane and you will be able to modify their default values. You can also edit the generated XAML in the XAML View or in Visual Studio.

ControlOuterBorder_Normal - a brush that represents the outer border color of the button, when it is in Normal state.

ControlBackground_Normal - a brush that represents the background color of the button, when it is in Normal state.

ControlForeground_Normal - a brush that represents the foreground color of the button, when it is in Normal state.

ControlOuterBorder_CornerRadius - represents the value for the radius of the button's corners.

ControlInnerBorder_Normal - a brush that represents the inner border color of the button, when it is in Normal state.

ControlOuterBorder_Focused - a brush that represents the outer border color of the button, when it is focused.

ControlBackground_Focused - a brush that represents the background color of the button, when it is focused.

ControlInnerBorder_Focused - a brush that represents the inner border color of the button, when it is focused.

ControlOuterBorder_MouseOver - a brush that represents the outer border color of the button, when the mouse is over it.

ControlBackground_MouseOver - a brush that represents the background color of the button, when the mouse is over it.

ControlInnerBorder_MouseOver - a brush that represents the inner border color of the button, when the mouse is over it.

ControlOuterBorder_Pressed - a brush that represents the outer border color of the button, when it is pressed.

ControlBackground_Pressed - a brush that represents the background color of the button, when it is pressed.

ControlInnerBorder_Pressed - a brush that represents the inner border color of the button, when it is pressed.

ControlOuterBorder_Disabled - a brush that represents the outer border color of the button, when it is disabled.

ControlBackground_Disabled - a brush that represents the background color of the button, when it is disabled.

ControlInnerBorder_Disabled - a brush that represents the inner border color of the button, when it is disabled.